Toggle mechanism for circuit breakers



May 17, 1966 G. s. HARPER 3,251,232

TOGGLE MECHANISM FOR CIRCUIT BREAKERS Filed June 25, 1964 4 Sheets-Sheetl May 17, 1966 Filed June 25, 1964 G. S. HARPER TOGGLE MECHANISM FORCIRCUIT BREAKERS 4 Sheets-Sheet 2 May 17, 1966 e. s. HARPER TOGGLEMECHANISM FOR CIRCUIT BREAKERS 4 Sheets-Sheet 5 Filed June 25, 1964 May17, 1966 s HARPER 3,251,232

TOGGLE MECHANISM FOR CIRCUIT BREAKERS Filed June 25, 1964 4 Sheets-Sheet4 United States Patent 3,251,232 TOGGLE MECHANISM FOR CIRCUIT BREAKERSGeorge S. Harper, Cambridge, Md., assignor to Airpax ElectronicsIncorporated, Cambridge, Md., a corporation of Maryland Filed June 25,1964, Ser. No. 377,993 7 Claims. (Cl. 74-2) This invention relates to atoggle mechanism for a circuit breaker. 1

Circuit breakers are often mounted on supports which are subject toshocks and/or vibrations of such violence and magnitude as to causeunwanted operation of the mechanism to open the circuit.

It is an object of this invention to provide a mechanism for maintainingthe circuit closed under conditions of great mechanical shock and/orvibration but which can be operated to quickly open the circuit underpredetermined electric current conditions.

It is alsoan object of this invention to provide a mechanism asaforesaid whereby the tenacity of the mechanism to maintain the circuitclosed can be releasedby a light tripping force.

It is a further object of this invention to produce a mechanism asaforesaid which is simple and reliable and in which the arrangement ofparts lends itselfto quick and easy assembly.

These and other objects of the invention Will be manifest from thefollowing description and accompanying drawings wherein:

FIG. 1 shows the mechanism in a position where the contacts are closed.

FIG. 2 shows the mechanism in a position Where the contacts are open.

FIG. 3 shows the mechanism in an intermediate postion.

FIG. 4 is a section taken on the line 4-4 of FIG. 2.

FIG. 5 is a section taken on the line 55 of FIG. 3 with certain partsomitted.

FIG. 6 is a view showing the symmetrical relationship of a part of thetoggle mechanism.

FIG. 7 is a view showing a modified mounting for the contact carryingarm.

FIG. 8 is a view on line 88 of FIG. 7.

In the drawings is shown a metal housing 2 having secured thereto athreaded bushing 4 in which is pivotally mounted a toggle handle orlever 6 on a pivot 8. A housing 10 of insulating material is fitted inthe metal housing 2 and is closed by a cover member 12 of insulatingmaterial and maintained in assembled relation by a metal cover member 14secured to housing 2.

Terminals 16, 18 are mounted by insulators 16', 18' in member 14.Terminal 16 has integral therewith a terminal 20 and terminal 18 hassecured thereto a fixed contact 22 for cooperation with a movablecontact 24 carried by a lever 26 pivotally and slidably mounted on aframe 28 by means of a pin 30 secured to the frame 28 and extendingthrough a slot 32 in the lever 26. A spring 34 is wound about pin 30 andis provided with a biasing arm 36 bearing against lever 26 and reactionarms 38 hearing against the frame 28.

A lever 40 of insulating material is pivotally mounted on the frame 28by a pivot rod 42 secured to the frame and is provided with a socketportion 44 for reception of the end of lever 6. Movement of the lever 6about pivot 8 rotates the lever 40 about pivot 42.

A U-shaped lever 46 (shown in FIG. 5) is pivotally connected to thelever 40 by a pivot 48 and a lever 50 is pivotally connected to lever 26by a pivot connection 52. The lever 50 is formed with parallel sidesconnected by a bridge piece 51 integral therewith and straddles lever 26to form a structure which is symmetrical to avoid any tendency for thelevers to bind or to bend the connecting pivot. The lever 46 is alsoformed with parallel sides which are connected by bridge pieces 47 toform an integral symmetrical structure which straddles lever 50. Levers46 and 50 are pivotally connected by a pivot connection 54. An L-shapedforked lever 56 is pivotally connected to the end of one of the legs ofthe U-shaped lever 46 by a pivot connection 58 and is shaped to allowthe. entrance and exit of a pin 60, secured to lever 50, into and out ofthe fork groove 61.

A shaft 62 is rotatably mounted on the U-shaped lever 46 and is providedwith a reduced section 64 which will allow the passage of the lever 56when rotated to the position shown in FIG. 3 but which will preventrotation of the lever 56 when positioned as shown in FIG. 1. The shaftis also provided with an abutment in the form of a pin 66 fixed thereto.

A bell crank lever 68 is pivoted on a rod 70 fixed to the frame and hasone arm 72 adjacent an electromagnet 74 and another arm 76 which cancontact and rotate the pin 66 when electromagnet 74 is energized toattract arm 72. The pin 66 is urged by a spring 78 into contact with anabutment 80 carried by lever 46. A second abutment 82 carried by thelever 46 serves as a reaction element for the spring 78.

The circuit breaker is shown in FIG. 1 with the contacts 22, 24 biasedtogether by spring 34. As a consequence the reaction force of spring 34on pivot 52 loads the levers 46 and 50 to tend to collapse them into theposition shown in FIG. 3. However collapse is prevented by the fit ofpin 60 in the fork groove 61. The force of pin 60 against lever 56 tendsto pivot the lever 56 about pivot 58 and into contact with shaft 62.Since the lever 56 is prevented by the shaft 62 from rotating to releasethe pin 60, the levers 46 and 50 are maintained locked in the positionshown in FIG. 1. Only shocks and/or vibrations of such'violence,magnitude, and character that can rotate shaft 62 against the bias ofspring 78 can cause unwanted collapse of the toggle mechanism. Upon theoccurrence of an overload the electromagnet 74 is energized to attractarm 72 and to cause pivoting of the bell-crank lever 68 about pivot 70.A pad 84 carried by the arm 76 is carried into contact with abutment pin66 to thereby rotate shaft 62. Rotation of the shaft from the lockingposition shown in FIG. 1 to the unlocking position as shown in FIG. 3presents the reduced section 62 to the end of the lever 56 to allow thelever to rotate to the position shown in FIG. 3 to thereby release pin60 and allow the collapse of the linkage .46, 50 to the position shown.The collapse of the linkage allows movement of lever 26 relative to pin30 and thus separate the contacts 22, 24. The are chute 86 serves toextinguish the are drawn by the separating contacts.

Springs 88 are wrapped about pivot 42 and have biasing arms 90 urgingpivot 48 about the pivot 42 and have a reaction arm 92 bearing againstthe frame 28 shown as a segment in FIG. 1. Immediately upon the collapseof the linkage to the position shown in FIG. 3, the arm 90 moves pivot48 and its connected lever 46 carrying lever 56 to the position shown inFIG. 2 whereby pin 60 is again received in fork groove 61 and lever 56held captive by shaft'62 to reform the toggle. The parts come to rest inthe position shown in FIG. 2.

To reset the device lever 6 is rotated counterclockwise about pivot 8.This rotates lever 40 clockwise about pivot 42 to carry pivot 48 aboutthis pivot until it comes to rest against a stop not shown. The levers46, 50

. locked against pivoting relative to each other are moved sliding ofthe contacts over each other gives the contacts a self-cleaning action.

A modified mounting for lever 26 is shown in FIGS. 7 V

and 8 wherein the lever is pivoted on pin 98, and pin 98 is pivotallyconnected to links 100 which are pivotally mounted on pins 102 securedto frame 28. A spring 104 is wound about pin 98 and is provided with abiasing arm 106 bearing against lever 26 and reaction arms 108 bearingagainst the links 100.

What is claimed is:

1. A toggle mechanism comprising a first lever pivotally and slidablymounted on a frame, a second lever pivotally mounted on the frame, apair of levers pivotally connected to each other and to said first andsecond levers respectively, means for locking said pair of leversagainst pivotal movement with respect to each other, and means forunlocking said locking means to permit pivotal movement of said pair oflevers with respect to each other, said locking means comprising aforked lever pivotally carried by one of said pair of levers, a pinreceived in the fork carried by the other of said pair of levers, andmeans holding the forked lever against pivotal movement.

2. A mechanism as in claim 1 wherein the means holding the forked leveragainst pivotal movement comprises a shaft rotatably mounted on said oneof said pair of levers and having a reduced section, means formaintaining the shaft against rotation with the reduced section out ofcontact with the lever, and means urging said forked lever, into contactwith the shaft.

3. A mechanism as in claim 2 wherein the means for unlocking the lockingmeans comprises means for rotating the shaft to present the reducedportion of the shaft to the lever;

4. A mechanism as in claim 3 wherein the means for rotating the shaftcomprises an abutment secured to the shaft and a lever pivoted on theframe for contact with the abutment.

5. A mechanism as in claim 3 wherein the means for rotating the shaftcomprises a bell-crank lever, an electromagnet mounted on the frameadjacent one arm of the crank for attracting said arm upon apredetermined current condition, and an abutment carried by the shaft inthe path of movement of the other arm of the crank for actuationthereby.

6. A toggle mechanism comprising a first lever, link means pivot-allymounting said lever on a frame, a second lever pivotally mounted on theframe, a pair of levers pivotally connected to each other and to saidfirst and second levers respectively, means for locking said pair oflevers against pivotal movement with respect to each other, and meansfor unlocking said locking means to permit pivotal movement of said pairof levers with respect to each other.

7. A toggle mechanism as in claim 6 wherein the link means comprises apair of links pivotally mounted on the frame and pivotally connected tothe first lever.

References Cited by the Examiner UNITED STATES PATENTS 2,556,054 6/1951Allan et al 74---2 X 2,802,922 8/1957 Page et a1 200-164 FOREIGN PATENTS708,012 7/1941 Germany.

MILTON KAUFMAN, Primary Examiner.

1. A TOGGLE MECHANISM COMPRISING A FIRST LEVER PIVOTALLY AND SLIDABLYMOUNTED ON A FRAME, A SECOND LEVER PIVOTALLY MOUNTED ON THE FRAME, APAIR OF LEVERS PIVOTALLY CONNECTED TO EACH OTHER AND TO SAID FIRST ANDSECOND LEVERS RESPECTIVELY, MEANS FOR LOCKING SAID PAIR OF LEVERSAGAINST PIVOTAL MOVEMENT WITH RESPECT TO EACH OTHER, AND MEANS FORUNLOCKING SAID LOCKING MEANS TO PERMIT PIVOTAL MOVEMENT OF SAID PAIR OFLEVERS WITH RESPECT TO EACH OTHER, SAID LOCKING MEANS COMPRISING AFORKED LEVER PIVOTALLY CARRIED BY ONE OF SAID PAIR OF LEVERS, A PINRECEIVED IN THE FORK CARRIED BY THE OTHER OF SAID PAIR OF LEVERS, ANDMEANS HOLDING THE FORKED LEVER AGAINST PIVOTAL MOVEMENT.